How does Johnson use repetition to support his meaning in the poem?

Jonson uses repetition and parallelism throughout his poem to enforce his meaning: namely, that the object of his affections pays too much mind to her physical appearance, which has the effect of obscuring her natural beauty. Arguably, he is talking about not only this particular woman, but complaining about the habits of women in general.
In the first stanza, the repetition of "still" has a cumulative effect; Jonson here uses enumeratio to set out the many rituals the woman undergoes: "still to be neat, still to be drest...Still to be powder'd, still perfum'd." The repetition builds to a climax, amplifying the sheer number of things that must be done, before the damning repetition of the final line: "All is not sweet, all is not sound." Here, the purpose of the repetition is to amplify the fact that such endless work has not had the desired effect: all is certainly not perfect.
Instead, Jonson sets out what he would prefer: "Give me...give me..." And yet the repetition in the second stanza occurs only once: Jonson does not wish to suggest that his own demands are excessive. Rather, the lack of repetition in the second half of the poem underlines the difference between its simplicity, echoing the simplicity of presentation Jonson calls for, and the busy overwork of the first stanza, reflecting the indulgence of effort focused on physical appearance.